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Achieving quantum-enhanced performances when measuring unknown quantities requires developing suitable methodologies for practical scenarios, that include noise and the availability of a limited amount of resources. Here, we report on the…

We investigate the precision limits and optimal protocols for sensing single qubit signals in the presence of erasure noise. We study a hierarchy of precision limits achievable with metrological strategies of differing complexity, and…

Quantum Physics · Physics 2026-03-13 Michal Arieli , Alex Retzker , Tuvia Gefen

Unconventional receivers enable reduction of error rates in optical communication systems below the standard quantum limit (SQL) by implementing discrimination strategies for constellation symbols that go beyond the canonical measurement of…

Quantum Physics · Physics 2019-10-01 L. Kunz , M. T. DiMario , F. E. Becerra , K. Banaszek

Homodyne measurement is a corner-stone of quantum optics. It measures the fundamental variables of quantum electrodynamics - the quadratures of light, which represent the cosine-wave and sine-wave components of an optical field and…

Long-distance fiber communication stands as a cornerstone of modern technology. One of the underlying principles, preventing signal levels from diminishing below the detectability threshold, is optical amplification. In particular,…

Quantum Physics · Physics 2023-09-15 Karol Łukanowski , Konrad Banaszek , Marcin Jarzyna

Quantum mechanics imposes a limit on the precision of a continuous position measurement of a harmonic oscillator, as a result of quantum backaction arising from quantum fluctuations in the measurement field. A variety of techniques to…

Quantum Physics · Physics 2019-05-09 Itay Shomroni , Liu Qiu , Daniel Malz , Andreas Nunnenkamp , Tobias J. Kippenberg

A major challenge in practical quantum computation is the ineludible errors caused by the interaction of quantum systems with their environment. Fault-tolerant schemes, in which logical qubits are encoded by several physical qubits, enable…

Quantum Physics · Physics 2020-12-17 Kai Sun , Jin-Shi Xu , Xiao-Ye Xu , Yong-Jian Han , Chuan-Feng Li , Guang-Can Guo

Based on the conventional Mach-Zehnder interferometer, we propose a metrological scheme to improve phase sensitivity. In this scheme, we use a coherent state and a squeezed vacuum state as input states, employ multi-photon-subtraction…

Quantum Physics · Physics 2025-05-08 Qisi Zhou , Qinqian Kang , Tao Jiang , Zekun Zhao , Teng Zhao , Cunjin Liu , Liyun Hu

We experimentally implement a machine-learning method for accurately identifying unknown pure quantum states. The method, called single-shot measurement learning, achieves the theoretical optimal accuracy for $\epsilon = O(N^{-1})$ in state…

Quantum Physics · Physics 2021-05-05 Sang Min Lee , Hee Su Park , Jinhyoung Lee , Jaewan Kim , Jeongho Bang

Estimation of the phase delay between interferometer arms is the core of transmission phase microscopy. Such phase estimation may exhibit an error below the standard quantum (shot-noise) limit, if the input is an entangled two-mode state,…

Quantum Physics · Physics 2024-07-18 Nilakantha Meher , Eilon Poem , Tomáš Opatrný , Ofer Firstenberg , Gershon Kurizki

Quantum target detection (QTD) utilizes nonclassical resources to enable radar-like detection for identifying reflecting objects in challenging environments, surpassing classical methods. To fully leverage the quantum advantage in QTD,…

Quantum Physics · Physics 2025-03-05 Wei-Ming Chen , Pin-Ju Tsai

Much of modern metrology and communication technology encodes information in electromagnetic waves, typically as an amplitude or phase. While current hardware can perform near-ideal measurements of photon number or field amplitude, to date…

We derive unified lower bounds on the mean squared error (MSE) of distributed quantum sensor fusion under Byzantine faults and decoherence. Building on the classical Brooks-Iyengar overlap function and its vector extension, the predictive…

Distributed, Parallel, and Cluster Computing · Computer Science 2026-05-20 Vasanth Iyer , S. S. Iyengar

By exploiting the exotic quantum states of a probe, it is possible to realize efficient sensors that are attractive for practical metrology applications and fundamental studies. Similar to other quantum technologies, quantum sensing is…

Quantum Physics · Physics 2022-07-06 W. Wang , Z. -J. Chen , X. Liu , W. Cai , Y. Ma , X. Mu , L. Hu , Y. Xu , H. Wang , Y. P. Song , X. -B. Zou , C. -L. Zou , L. Sun

Phase-sensitive optical parametric amplification of squeezed states helps to overcome detection loss and noise and thus increase the robustness of sub-shot-noise sensing. Because such techniques, e.g., imaging and spectroscopy, operate with…

Quantum Physics · Physics 2021-05-10 Gaetano Frascella , Roman V. Zakharov , Olga V. Tikhonova , Maria V. Chekhova

We show that it is possible to use the spatial quantum correlations present in twin beams to extract information about the shape of a mask in the path of one of the beams. The scheme, based on noise measurements through homodyne detection,…

Quantum Physics · Physics 2015-06-04 A. M. Marino , J. B. Clark , Q. Glorieux , P. D. Lett

Mean squared error (MSE) is one of the most widely used metrics to expression differences between multi-dimensional entities, including images. However, MSE is not locally sensitive as it does not take into account the spatial arrangement…

Computer Vision and Pattern Recognition · Computer Science 2022-06-02 Amogh Gudi , Fritjof Büttner , Jan van Gemert

Quantifying nonclassicality of a bosonic mode is an important but challenge task in quantum optics. Recently, the first nonclassicality measure based on the concept of operational resource theory has been proposed [Phys. Rev. Research 2,…

Quantum Physics · Physics 2020-10-14 Wenchao Ge , M. Suhail Zubairy

In distributed quantum sensing the correlations between multiple modes, typically of a photonic system, are utilized to enhance the measurement precision of an unknown parameter. In this work we investigate the metrological potential of a…

Quantum Physics · Physics 2023-03-29 Jose Carlos Pelayo , Karol Gietka , Thomas Busch

Physical realizations of the canonical phase measurement for the optical phase are unknown. Single-shot phase estimation, which aims to determine the phase of an optical field in a single shot, is critical in quantum information processing…

Quantum Physics · Physics 2022-08-16 M. A. Rodríguez-García , M. T. DiMario , P. Barberis-Blostein , F. E. Becerra